The production and release of catecholamines by the kidney are being studied in the anesthetized dog. We are using simultaneous sampling from the aorta, renal veins, and ureters. This is done in conjunction with measurements of arterial blood pressure, renal blood flow and glomerular filtration rate to allow for an overall assessment of these physiologic interactions. The acute effects of unilateral renal artery constriction and ipsilateral renal denervation on the above parameters is also being evaluated. The arterial-venous difference across the kidney decreases for epinephrine and increases for norepinephrine. This indicates norepinephrine production and release. Both unilateral artery constriction and denervation decrease the norepinephrine release bilaterally. In addition, prolonged anesthesia produces a gradual decline in plasma and urine levels of epinephrine, norepinephrine and dopamine.